Spark plug



H. WALKER.

SPARK PLUG.

APPLICATION FILED 00111.1919.

1,41 36; Patented Mar. 28, 1922.

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Specification of Letters Eatent. Patented Mam 28, 1922.

Application filed October 17, 1919. Serial No. 381,e06.

To all whom it may concern:

Be it known that I, HERBERT WALKER, a subject of the King of Great Britain, and resident of the cit; of Toronto, county of York, Province of ntario in the Dominion of Canada, have invented certain new and useful Improvements in Spark Plugs, described in the following specification and illustrated in the accompanying drawings, that form part of the same.

The principal objects of this invention are, to obviate the difficulties experienced through the accumulation of carbon on the plug terminals and to increase the efi'ectiveness of the explosion.

A still further and very important object is to eliminate the possibility of the sparking points of the plug becoming fouled with oil.

The principal feature of the invention consists in the novel construction, whereby the sparking points are enclosed within a shroud having an opening to admit the combustible gas. 1

In the drawings, Figure 1 is an elevational view of my improved sparking plug.

Figure 2 is a longitudinal sectional View.

Figure 3 is a top plan view of thepoint enclosing shroud removed from the plug.

It is well known that one of the greatest difficulties in maintaining proper operating conditions of internal combustion engines is keeping the sparking points of the plug free from carbon and oil.

v The present invention accomplishes this result in a remarkable manner by a very simple structure. The threaded casing 1 of the plug in which is secured the porcelain 2 has its inner wall 3 threaded at the inner end. Into this threaded inner wall secured a cup-shaped shroud 4 and said shroud is formed with a small central hole 5 at the inner and through which the central terminal 6 of the plug projects. The hole 5 is of slightly larger diameter than the terminal, leaving a space therearound through which the combustible gas may pass. One or more points 7 are secured in the side wall of the shroud 4 and project inwardly having their terminal ends arranged close to the centre terminal.

The shroud completely encloses the sparking terminal points so that oil splashing in the cylinders will be kept from contact with said points but free access of the combustible gases is permitted through the centre hole 5.

It will be seen that it will be impossible for oil to find its Way into the interior of the shroud, consequently the' gas will be clean and any oil accumulating around the edge of the sole 5 or around the central terminal 6 will upon the ignition of the gas within the shroud be immediately blown out through the hole 5. The small quantity of gas contained within the shroud receives the ignition and blows a flame out through the opening around the central terminal, thus igniting the main charge surrounding the plug. This action automatically clears the plug at every explosion of all accumulations which may possibly occur around the opening and the sparking points are maintained in a clean condition;

In the event of foreign matter getting into the interior of the shroud through any possible mischance it will be seen that the plug may be readily cleansed by simply unscrewing the plug from the shroud and the points 7 will be removed from their proximity to the central terminal 6 and the terminal ma be thoroughly cleaned in a manner which is impossible with the present forms of plugs and as the central terminal is removed the outer points will also be more accessible. The shroud may be very easily washed to remove any accumulation of foreign matter.

The advantages to be obtained from the use of a plug such as described are very numerous and its use greatly enhances the operative conditions of the engines.

What I claim as my invention is A spark plug having an internally threaded annular projection surrounding the central terminal, a cap externally threaded and fitting the internal thread on said projec-' tion and having a small central opening, and

a plurality of sparking' terminals secured in the side wall of said cap extending inwardly in substantial tangential arrangement with the central terminal and capable of adjustment in relation thereto.

. HERBERT WALKER. 

